Yes, you have to go around in Johto until you meet him, will appear on your poke map

Yes, someone in violet city I believe, not entirely sure, he will give you the dowsing machine which is the pokeradar, and it will allow you to find items

You have to sneak up on it and get behind it

You have to search deeply into whirl islands.

Weaken Lugia and then use any ball that you have and keep trying that ball. Eventually you will catch it

I have the same problem. But I tried a premier ball once and almost caught it